* Fixes bug in imgaug.Hue

Hue range of cv2.cvtColor() is 0-360 for floating point images (and 0-180 for 8-bit images), see
https://docs.opencv.org/3.2.0/de/d25/imgproc_color_conversions.html#color_convert_rgb_hsv.

* fix lint

* add link about opencv hue range

* add enhancenet

* fix liniting

* another battle against Python3 linter

* fix gram matrix

* follow suggestions

* fix suggestions

* add teaser again

* small docs & style fix

* simplify VGG mean

* small changes

* switch to space_to_batch

* Refactoring javascript to show class name

* fixing group name

* fixing group name

* fixing group name

* Atari Visualization Bugfix

OpenCV2 does not always display the visualization properly. 

For imshow to properly update, cv2.waitKey should be called. Without this line, the cv2 window does not refresh on my system with OpenCV version 2.4.9.1 on Debian with Python 2.7.9. More info can be found on [StackOverflow](https://stackoverflow.com/questions/44854699/why-does-the-cv2-imshow-does-not-render-without-cv2-waitkey).

* Remove unused import